Enbridge Mackinac Pipline: Nearly 250 Places In Which Pipe Was Unsupported, Broke Safety Regs
Last edited Sat Jun 3, 2017, 02:02 PM - Edit history (1)
State and federal documents indicate that for years the Enbridge Line 5 pipeline under the Straits of Mackinac was out of compliance with easement rules that govern how far the twin pipes can span the lake bottom unsupported.
Although Enbridge's 1953 easement with the state of Michigan specifies the pipeline must have anchor supports across any gaps in the lakebed span greater than 75 feet, a 2003 survey identified 16 unsupported spans greater than 140 feet, with the longest being 224 feet on the east pipe and 286 feet on the west pipe. The 286-foot unsupported span was nearly four times the allowable length.
The unsupported spans were identified in an October 2016 engineering report prepared by Kiefner & Associates for Enbridge as part of its negotiated settlement with the federal government over the 2010 Kalamazoo River oil spill. Line 5 inspection reports submitted to a state pipeline board also document nearly 250 instances between 2005 and the most recent inspection in 2016 where unsupported spans on the twin lines have exceeded the 75-foot mark.
Enbridge says it has anchored all previously unsupported spans, but critics say the damage may already be done and that allowing such unsupported span lengths to go unattended for years may have irrevocably compromised the structural integrity of the pipeline, which carries light crude oil and natural gas liquids.
EDIT
http://www.mlive.com/news/index.ssf/2017/06/line_5_unsupported_spans.html#incart_river_index
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